Generally, as power is the rate at which energy is delivered while the unit to measure power is the watt (W) and energy is measured in joules (J), both “joule” and “watt” can be used as the common units for electrical energy consumption. However, since power (watts) is the product of voltage (volts) and current (amperes), most power measuring devices or methods that are currently available are instruments used for measuring electrical voltage or current in an electric circuit. Nevertheless, it would be very helpful in self-control energy conservation if there is a kind of communication means that can be integrated in those measuring devices for effectively transmitting the measuring results to either a central control or a user.
For the most common electrical sensors that are available today, they are generally bulky in size, required to be powered by external power sources and incapable of being applied directly to multi-wire cables, etc., that the usage of such electrical sensors are limited. On the other hand, there is already a novel micro-electro-mechanical system (MEMS) electrical sensor that is being developed based upon the Lorentz force principle and is designed to measure current according to mechanical deformation. Although the MEMS electrical sensor is freed from the shortcomings of the aforesaid conventional electrical sensors, it is still unable to meet the future performance requirement. Therefore, it is in need of a easy-to-install, miniature, non-contact, passive electrical sensor that is able to measure simultaneously the voltage value and current value in a power cable, by that power consumption information of any electrical equipments can be acquired easily and fully for achieving self-control energy saving.